Method for treating neoadjuvant chemotherapy-induced metastasis

ABSTRACT

Methods of reducing chemotherapy-induced metastasis, or chemotherapy-induced cancer cell dissemination, for patients subject to chemotherapy using Tie-2 inhibitors. Methods of reducing chemotherapy-induced metastasis, or chemotherapy-induced cancer cell dissemination, for patients subject to chemotherapy using inhibitors of Mena expression and/or function are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.62/512,298, filed May 30, 2017 and U.S. Provisional Application No.62/524,690, filed Jun. 26, 2017, the contents of each of which arehereby incorporated by reference.

STATEMENT OF GOVERNMENT SUPPORT

This invention was made with government support under grant numbersCA100324, CA150344, CA170507 and CA200561 awarded by the NationalInstitutes of Health. The government has certain rights in theinvention.

BACKGROUND OF THE INVENTION

Throughout this application various publications are referred to. Thedisclosures of these publications, and of all patents, patentapplication publications and books referred to herein, are herebyincorporated by reference in their entirety into the subject applicationto more fully describe the art to which the subject invention pertains.

Breast cancer cell intravasation and dissemination occur atmicroanatomical structures called Tumor MicroEnvironment of Metastasis(TMEM). Each TMEM is composed of three different cell types in directphysical contact: a tumor cell expressing the actin-regulatory proteinMammalian-enabled (Mena), a perivascular macrophage and an endothelialcell (1, 2). TMEM sites have been identified in mouse and human mammarycarcinomas, and their density correlates with metastatic outcome inbreast cancer patients (3-5). High-resolution intravital imaging (IVI)of murine primary breast tumors revealed that TMEM sites induce localand transient dissociation of endothelial cell junctions through whichmigratory cancer cells may intravasate and disseminate to secondarysites (1). TMEM-dependent vascular permeability is particularlylocalized, and is mediated by vascular endothelial growth factor-A(Vegf-A) release from the TMEM-bound Tie2hi/Vegfhi macrophage (1).

Randomized prospective studies indicate that addition of paclitaxel intothe preoperative neoadjuvant chemotherapy (NAC) regimen significantlyincreases the rate of pathologic complete response (pCR), butparadoxically does not improve the overall survival (6, 7). It has beenalso shown in mouse breast cancer models that taxane-basedchemotherapies, if discontinued, promote tumor regrowth by inducingangiogenesis. In particular, they mobilize bone marrow-derivedmesenchymal and endothelial progenitors and CD11b+ myeloid cells,including Tie2+ monocytes, into the primary tumor microenvironment(8-13). Tie2+ monocyte progenitors transform into Tie2hi macrophages,which associate with newly constructed tumor blood vessels and promotetumor regrowth (14, 15). As stated before, Tie2hi macrophages are alsocritical constituents of the functional TMEM sites, where they mediateVegf-induced blood vessel permeability and tumor cell intravasation.

TMEM-dependent vascular permeability is necessary but not sufficient fortumor cell intravasation, because intravasation also requires presenceof discohesive, migratory cancer cells (1, 16-18). These migratory cellsexpress high levels of invasive, chemotactic pro-metastatic Mena isoformMena^(INV), and low levels of the anti-metastatic Mena isoform, Mena11a(18-26). We have previously documented that Mena^(INV) expression isswitched on in invasive tumor cells by Notch-mediated macrophage contactand signaling (27). Furthermore, it is known that paclitaxel inducesinflux of macrophages into the primary tumor which are required for TMEMassembly and function (1, 2, 19, 20, 28, 29)

The present invention addresses the need for improved anti-metastatictherapies, including for patients with localized disease treated withchemotherapy before the removal of the primary tumor (neoadjuvantsetting).

SUMMARY OF THE INVENTION

A method of treating a subject for a tumor, wherein the subject hasreceived or is receiving chemotherapy treatment for the tumor,comprising

a) identifying the subject as having an increased risk of metastasis inresponse to chemotherapy by performing or having performed aquantification of Mena^(Calc), Mena^(INV) or a TMEM score of the tumor,and comparing to a predetermined control level of Mena^(Calc) Mena^(INV)or TMEM score, wherein a subject having a Mena^(Calc), Mena^(INV) or aTMEM score above the respective predetermined control level identifiesthe subject as having an increased risk of metastasis, andb) when a subject is identified in step a) as having an increased riskof metastasis in response to chemotherapy, either (1) ceasingchemotherapy on the subject and administering a targeted therapy,immunotherapy or radiotherapy to treat the cancer, or (2) administeringa chemotherapy and an amount of (i) a Tie-2 inhibitor effective toreduce chemotherapy-induced metastasis or chemotherapy-induced cancercell dissemination, or (ii) a TMEM activity inhibitor, to the subjecteffective to treat a tumor.

A method of reducing chemotherapy-induced metastasis, orchemotherapy-induced cancer cell dissemination, comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of (i) an inhibitor of Mena function or (ii) aninhibitor of Mena expression effective to reduce chemotherapy-inducedmetastasis or chemotherapy-induced cancer cell dissemination.

A method of reducing chemotherapy-induced tumor microenvironment ofmetastasis (TMEM) activity in a patient comprising administering, to apatient with a cancer subject to a chemotherapy treatment, an amount of(i) an inhibitor of Mena function or (ii) an inhibitor of Menaexpression effective to reduce chemotherapy-induced TMEM activity.

A method of inhibiting metastasis of a cancer comprising administering,to a patient with a cancer, an amount of (i) an inhibitor of Menafunction or (ii) an inhibitor of Mena expression effective to inhibitmetastasis of a cancer.

A method of reducing chemotherapy-induced metastasis, orchemotherapy-induced cancer cell dissemination, is provided comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of a Tie-2 inhibitor effective to reducechemotherapy-induced metastasis or chemotherapy-induced cancer celldissemination.

Also provided is a method of reducing chemotherapy-induced tumormicroenvironment of metastasis (TMEM) activity in a patient comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of a Tie-2 inhibitor effective to reducechemotherapy-induced TMEM activity.

Also provided is a method of inhibiting metastasis of a cancercomprising administering, to a patient with a cancer, an amount of aTie-2 inhibitor effective to inhibit metastasis of a cancer.

A method for identifying a subject as likely having a poor long-termresponse to chemotherapy comprising determining, in a sample obtainedfrom the subject, the level of Mena^(Calc), Mena^(INV) or a TMEM scorethereof, and comparing to a predetermined control level of Mena^(Calc),Mena^(INV) or TMEM score, respectively, and identifying the subject ashaving a poor long-term response to chemotherapy wherein a subject isidentified as likely having a poor long-term response to chemotherapywhen the sample obtained from the subject has a level of Mena^(Calc),Mena^(INV) or TMEM score above the predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively.

A method for identifying a subject as likely having a tumor resistant toa receptor tyrosine kinase (RTK) inhibitor therapy comprisingdetermining, in a sample of the tumor obtained from the subject, thelevel of Mena^(Calc), Mena^(INV) or a TMEM score thereof, and comparingto a predetermined control level of Mena^(Calc), Mena^(INV) or TMEMscore, respectively, and identifying the subject as having a tumorresistant to RTK inhibitor therapy, wherein a subject is identified aslikely having a tumor resistant to RTK inhibitor therapy when the sampleobtained from the subject has a level of Mena^(Calc), Mena^(INV) or TMEMscore above the predetermined control level of Mena^(Calc), Mena^(INV)or TMEM score, respectively.

A method for identifying a subject as likely having a tumor resistant toa receptor tyrosine kinase (RTK) inhibitor and cytotoxic chemotherapycombination therapy comprising determining, in a sample of the tumorobtained from the subject, the level of Mena^(Calc), Mena^(INV) or aTMEM score thereof, and comparing to a predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively, and identifying thesubject as having a tumor resistant to RTK inhibitor and cytotoxicchemotherapy combination therapy, wherein a subject is identified aslikely having a tumor resistant to RTK inhibitor therapy and cytotoxicchemotherapy combination therapy when the sample obtained from thesubject has a level of Mena^(Calc), Mena^(INV) or TMEM score above thepredetermined control level of Mena^(Calc), Mena^(INV) or TMEM score,respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1H. Paclitaxel Delays Tumor Growth while Promoting Infiltrationof Tie2^(hi)/Vegf^(hi) Macrophages and TMEM Assembly: (A) Experimentaldesign and cohort composition. (B) TMEM score in mice treated as shownin the experimental design and TMEM identification by triple-stainimmunohistochemistry (IHC). Upper graph, TMEM score assessed in 10high-power fields (HPFs) by two pathologists; lower panel,representative images for each mouse model. Mann-Whitney U-test. (C)Perivascular Iba1⁺ macrophages in 10 HPFs (absolute counts) inPyMT-spontaneous and HT17-xenograft tumors treated with paclitaxel orvehicle control. Mann-Whitney U-test. (D) PerivascularTie2^(hi)/Vegf^(hi) macrophages in 10 HPFs (absolute counts) quantifiedin PyMT-spontaneous and HT17-xenograft tumors, treated with paclitaxelor vehicle control. Mann-Whitney U-test. (E) Immunofluorescence (IF) ofIba1, Cd31, Tie2, Vegf and DAPI in two sequential sections of anMMTV-PyMT breast tumor not treated with paclitaxel. RepresentativeVegf^(hi)/Tie2^(hi) macrophage (also co-expressing Iba1) encircled withyellow dotted line (F) IF of Iba1, Cd31, Vegf and DAPI in anHT17-xenograft tumor treated with paclitaxel, demonstrating a Vegf^(hi)and a Vegf^(lo) macrophage in the same field of view. (G-H) Correlationsof macrophage infiltration (Iba1⁺ macrophages or Vegf^(hi)/Tie2^(hi)macrophages) with TMEM Score in the PyMT-spontaneous (G) andHT17-xenograft (H) models (R²=Pearson's Coefficient of Determination);filled circles, control; open circles, paclitaxel.

FIG. 2A-2F. Paclitaxel Induces Vascular Permeability Exclusively at TMEMSites: (A) Experimental design and cohort composition. (B) Two examplesof images taken from a cfms-CFP mouse grafted with MMTV-PyMT/Dendra2⁺tumor. Bursting at TMEM (TMEM activity) identified by the presence oftetramethylrhodamine(TMR)-conjugated 155 kDa Dextran in theextravascular space (left image). Outline of the burst is indicated bydotted yellow line. Right image demonstrates absence of bursting atTMEM, as a control. Mφ, macrophage; TC, tumor cell; EC, endothelialcell. (C) Left; regions of interest (ROI) selection for calculation ofDendra2/TMR signal intensity over time. Right; the quantification ofextravascular dextran (red lines) and dendra2-labeled intravasatingcancer cell (green lines) signal intensity in the selectedTMEM-associated (straight lines) or away from TMEM (dotted lines) ROIsfrom the image on the left. (D) Normalized fluorescence intensity ofDextran-TMR, averaged from all bursting sites. (E) IF of endomucin(first column), Dextran-TMR (second column), their merged image (thirdcolumn), the corresponding thresholded blood vessel and extravasculardextran masks (fourth column) and the corresponding sequential sectionof TMEM IHC (fifth column) in MMTV-PyMT mice treated with paclitaxel.Upper row, TMEM-associated vascular profile; lower row, vascular profileaway from TMEM. (F) Percentage of vascular profiles with extravasculardextran that have at least one TMEM site or no TMEM sites associatedwith them for vehicle-treated (left graph) or paclitaxel-treated (rightgraph) cases.

FIG. 3A-3J. Paclitaxel Promotes TMEM-Dependent Vascular Permeability,Cancer Cell Dissemination and Metastasis in Breast Cancer. (A) Timelapse images of Supplementary Videos 1 (upper row) and 2 (lower row).Time shown in minutes (t=0′-20′). Arrowhead; site of bursting in apaclitaxel-treated mouse (active TMEM). (B) Incidence of bursting (atleast 1 complete event during 4.5-h of imaging per mouse) inpaclitaxel-treated and vehicle-treated MMTV-PyMT/Dendra2 cfms-CFP mice.(C) Frequency of bursting in paclitaxel and control MMTV-PyMT/Dendra2cfms-CFP mice. Mann-Whitney U-test. (D) Representative blood vessel(endomucin) and extravascular dextran masks, as obtained by IF in micetreated with either vehicle or paclitaxel, showing TMEM-associatedvascular permeability. (E) Quantification of extravascular dextran areanormalized to blood vessel area in mice treated with either vehicle orpaclitaxel shown in D. Mann-Whitney U-test. (F) Circulating tumor cellsper mL of blood collected before sacrifice (day 15). Values normalizedto the control group in each case to account for inter-cohortvariability. Mann-Whitney U-test. (G) Correlation between CTCs and TMEM(R²=Pearson's Coefficient of Determination); filled circles, control;open circles, paclitaxel. (H) Incidence of lung metastasis in micetreated with paclitaxel or vehicle control. Lower panels show two casesof histologically-detectable metastases in lungs of PyMT-transplants andHT17-xenografts, respectively. (I) Quantification ofhistologically-detectable lung metastases in mice treated withpaclitaxel or vehicle control. Mann-Whitney U-test. (J) Left:Quantification of single cancer cell dissemination in lungs ofPyMT-transplants using fluorescent stereomicroscopy. Right: Bloodvessels visualized via tail-vein injection of rhodamine-labeled lectin1-h before sacrifice and cancer cells identified through Dendra2expression (arrow). Mann-Whitney U-test.

FIG. 4A-4F. Paclitaxel Promotes the Expression of Invasive Isoforms ofMena in the Primary Breast Cancer Microenvironment. (A-D)Gene-expression levels of Mena or Mena isoforms (real-time RT-PCR)following RNA extraction from formalin-fixed paraffin-embedded (FFPE)tumors. Gene expression levels of Pan-Mena (A), Mena11a (B), Mena^(Calc)(C) and Mena^(INV) (D) indicated. Mann-Whitney U-test. (E) Correlationsof Mena^(calc) with TMEM and Mena^(INV) gene-expression with TMEM in thePyMT-spontaneous and HT17-xenograft tumors (R²=Pearson's Coefficient ofDetermination). Filled circles, control; open circles, paclitaxel. (F)Mena protein expression visualized by Mena^(INV) immunofluorescence andDAPI in PyMT-spontaneous and HT17-xenograft tumors, treated withpaclitaxel or vehicle control. (G) Quantification of theMena^(INV)-positive area (%) in tumors shown in F. Mann-Whitney U-test.

FIG. 5A-5E. Paclitaxel Promotes Breast Cancer Cell Dissemination andMetastasis in a Mena-Dependent Manner. (A) Experimental design andcohort composition. (B) IF of Iba1, Cd31, Vegf and DAPI in a Mena^(−/−)MMTV-PyMT-CFP-transplanted tumor, treated with either paclitaxel (lowerpanel) or vehicle control (upper panel). Arrowheads; Vegf^(hi)/Iba1⁺macrophages. (C) Perivascular Iba1+ macrophages counted in 10 HPFs(absolute counts) in Mena−/− MMTV-PyMT-CFP-transplanted tumors treatedwith paclitaxel or vehicle control. Mann-Whitney U-test. (D-E)Perivascular Tie2^(hi)/Vegf^(hi) macrophages quantified in Mena^(−/−)MMTV-PyMT-CFP-transplanted tumors, treated with paclitaxel or vehiclecontrol. Absolute counts (D) or proportion (E) among all perivascularIba1⁺ macrophages. Mann-Whitney U-test. (F) CTCs/mL blood collected fromMena^(+/+) and Mena^(−/−) PyMT-CFP mice. Values normalized to thecontrol group in each case to account for inter-cohort variability.Mann-Whitney U-test. (G) Quantification of single cancer celldissemination in the lungs of Mena^(+/+) and Mena^(−/−) PyMT-CFPtransplants, using fluorescent stereomicroscopy. Mann-Whitney U-test.This is the first demonstration that Mena expression and activity isnecessary for chemo-induced dissemination and that Mena inhibition willblock dissemination. Note that CTC count in FIG. 5F is a direct measureof TMEM activity in this experiment.

Therefore, agents that block Mena expression and/or that inhibit theinteraction of Mena with its target proteins, including PTP1b,SHIP2,Rac1 and the RTKs mentioned in the claims (see Eddy et al 2017TICB FIGS. 1 and 2), will inhibit the same activities claimed for theTIE2 inhibitors.

FIG. 6A-6E: Pro-metastatic changes of the breast tumor microenviromentmay be also mediated by chemotherapies other than taxanes. (A)Experimental design and cohort composition. (B) Representativehistological (H&E) and TMEM IHC sections in 40× magnification from PyMTmice receiving doxorubicin/cyclophosphamide treatment or vehiclecontrol, as shown in A. (C) TMEM score in MMTV-PyMT mice treated witheither vehicle-control or doxorubicin/cyclophosphamide. Mann-WhitneyU-test. (D) Circulating tumor cells per mL of blood collected beforesacrifice (day 15). Values normalized to the control group in each case,to account for inter-cohort variability. Mann-Whitney U-test. (E)Proportion of perivascular Tie2^(hi)/Vegf^(hi) macrophages among allIba1⁺ macrophages, quantified in MMTV-PyMT mice treated with either ordoxorubicin/cyclophosphamide or vehicle control. Mann-Whitney U-test.

FIG. 7A-7F: Neoadjuvant Chemotherapy in Breast Cancer Patients PromotesTMEM Assembly and Increased Mena^(INV) Expression. (A) Individual TMEMscores of 20 patients before and after receiving NAC, which includedweekly paclitaxel (80 mg/m²×12 consecutive weeks) followed sequentiallyby dose-dense AC chemotherapy (doxorubicin 60 mg/m2 and cyclophosphamide600 mg/m2 every 2 weeks×4 cycles, plus pegrastim 6 mg SC on day 2 ofeach cycle). The patients did not receive Tamoxifen. Red line; TMEMhigh-risk cutoff point (5). (B) Representative images of TMEMtriple-stain IHC in patients #3 and #7 in the pre-NAC core biopsies(upper panels) and post-NAC resected tumors (lower panels). (C) MeanTMEM scores in the 20 human breast cancers shown in A, before and afterreceiving NAC. Wilcoxon test. (D) Representative images of Mena^(INV)protein expression, as visualized by Mena^(INV) immunofluorescence andDAPI in a patient receiving NAC. (E) Quantification of theMena^(INV)-positive area in pre- and post-NAC patient samples. Assayperformed in only 7 of the patients shown in A, because of limitedavailability of pre-NAC biopsy material for the remaining 13 patients.Mann-Whitney U-test. (F) Mena^(INV) gene expression, as assessed byreal-time RT-PCR, in fine needle aspiration (FNA) biopsies taken from 5breast cancer patients before and after 2-weeks of receiving NAC withpaclitaxel.

FIG. 8A-8J: The Tie2 Inhibitor Rebastinib Eliminates the Pro-metastaticEffects of Paclitaxel. (A) Experimental design and cohort composition.(B-C) TMEM scores in the PyMT-transplantation model (B) and theHT17-xenograft model (C), treated with vehicle control or rebastinib, orpaclitaxel, or combination of rebastinib with paclitaxel. Mann-WhitneyU-test. (D-E) Perivascular Tie2^(hi)/Vegf^(hi) macrophages quantified in10 HPFs in the PyMT-transplantation model (D) or in the HT17-xenograftmodel (E), treated with vehicle control or rebastinib or paclitaxel orcombination of rebastinib with paclitaxel. Mann-Whitney U-test. (F-G)Circulating tumor cells/mL of blood collected before sacrifice (day 15)of mice (PyMT-transplantation, F; HT17-xenograft, G). Values normalizedto the control group in each case to account for inter-cohortvariability. Mann-Whitney U-test. (H) Incidence of bursting (at least 1complete event during 4.5-h of imaging per mouse) in paclitaxel-treatedMMTV-PyMT/Dendra2 cfms-CFP mice that either received or did not receiverebastinib. (I) Frequency of bursting in paclitaxel-treatedMMTV-PyMT/Dendra2 cfms-CFP mice that either received or did not receiverebastinib. Mann-Whitney U-test. (J) Proposed Model ofchemotherapy-induced pro-metastatic changes and Cancer CellDissemination. Chemo treatment increases the density ofTie2^(hi)/Vegf^(hi) macrophages within the primary tumor. Besidesinducing angiogenesis, these macrophages assemble active TMEMstructures. Paclitaxel treatment also increases expression of theactin-regulatory protein Mena^(INV) isoform in tumor cells due to theircontact with infiltrating macrophages, which in turn generates ahighly-migratory and invasive subpopulation of cancer cells and TMEMassembly. Together, paclitaxel-mediated TMEM-assembly and Mena^(INV)overexpression in breast cancer contribute to TMEM-dependent cancer celldissemination and distant metastasis. Targeting the function ofTMEM-associated macrophage subpopulation by Tie2 inhibitors counter-actsTMEM-mediated cancer cell dissemination induced by paclitaxel treatment.

DETAILED DESCRIPTION OF THE INVENTION

A method of treating a subject for a tumor, wherein the subject hasreceived or is receiving chemotherapy treatment for the tumor,comprising

a) identifying the subject as having an increased risk of metastasis inresponse to chemotherapy by performing or having performed aquantification of Mena^(Calc), Mena^(INV) or a TMEM score of the tumor,and comparing to a predetermined control level of Mena^(Calc) Mena^(INV)or TMEM score, wherein a subject having a Mena^(Calc), Mena^(INV) or aTMEM score above the respective predetermined control level identifiesthe subject as having an increased risk of metastasis, andb) when a subject is identified in step a) as having an increased riskof metastasis in response to chemotherapy, either (1) ceasingchemotherapy on the subject and administering a targeted therapy,immunotherapy or radiotherapy to treat the cancer, or (2) administeringa chemotherapy and an amount of (i) a Tie-2 inhibitor effective toreduce chemotherapy-induced metastasis or chemotherapy-induced cancercell dissemination, or (ii) a TMEM activity inhibitor, to the subjecteffective to treat a tumor.

In an embodiment, wherein when a subject is identified in step a) ashaving an increased risk of metastasis in response to chemotherapy, thechemotherapy and an amount of (i) a Tie-2 inhibitor effective to reducechemotherapy-induced metastasis or chemotherapy-induced cancer celldissemination, or (ii) a TMEM activity inhibitor, is administered to thesubject.

In embodiments, wherein the TMEM activity inhibitor comprises a CSF1Rinhibitor, a VEGFR inhibitor, or a MENA inhibitor.

In embodiments, the method further comprises obtaining a predeterminedcontrol level for Mena^(Calc), Mena^(INV) or TMEM score for the subjectby obtaining a Mena^(Calc) Mena^(INV) or TMEM score from a tumor samplefrom the subject prior to any chemotherapy being initiated on thesubject.

In embodiments, the Tie-2 inhibitor is administered.

In embodiments, the Tie-2 inhibitor is rebastinib(4-[4-[(5-tert-butyl-2-quinolin-6-ylpyrazol-3-yl)carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide).

In embodiments, the chemotherapy is an anti-tubulin chemotherapy.

In embodiments, the chemotherapy is a taxane.

In embodiments, the chemotherapy is paclitaxel or eribulin.

In embodiments, the tumor is a breast cancer tumor.

In embodiments, the breast cancer is an adenocarcinoma.

In embodiments, the breast cancer is Human Epidermal Growth Factor 2Negative.

In embodiments, the breast cancer is a recurrent breast carcinoma.

In embodiments, the breast cancer is a Stage IV breast cancer.

In embodiments, the chemotherapy is a neoadjuvant therapy.

In embodiments, the metastasis is a lung metastasis, bone metastasis,lymph node metastasis, liver metastasis or brain metastasis.

In embodiments, the method may be performed when the patient has startedchemotherapy within the last day or week. In embodiments, the method maybe performed when the patient has been on a course of chemotherapy. Inembodiments the method may be performed so as to determine the futuretreatment of the tumor in the subject. In embodiments the method may beperformed so as to determine the effectiveness of the current treatmentof the tumor in the subject and/or make treatment decisions.

A method of reducing chemotherapy-induced metastasis, orchemotherapy-induced cancer cell dissemination, comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of (i) an inhibitor of Mena function or (ii) aninhibitor of Mena expression effective to reduce chemotherapy-inducedmetastasis or chemotherapy-induced cancer cell dissemination.

A method of reducing chemotherapy-induced tumor microenvironment ofmetastasis (TMEM) activity in a patient comprising administering, to apatient with a cancer subject to a chemotherapy treatment, an amount of(i) an inhibitor of Mena function or (ii) an inhibitor of Menaexpression effective to reduce chemotherapy-induced TMEM activity.

A method of inhibiting metastasis of a cancer comprising administering,to a patient with a cancer, an amount of (i) an inhibitor of Menafunction or (ii) an inhibitor of Mena expression effective to inhibitmetastasis of a cancer.

In an embodiment, the inhibitor of Mena is an interfering-RNA, aninterfering-microRNA, a Mena gene edit, or a Mena gene splicingsuppressor. In an embodiment, the inhibitor of Mena is an inhibitor ofMena function and is a small molecule inhibitor of, or an aptamer whichinhibits, Mena's interaction with a target protein. In an embodiment,the inhibitor of Mena is an inhibitor of Mena's interaction with atarget protein which is PTP1b, SHIP2, Rac1 or a receptor tyrosinekinase.

In an embodiment, two or more Mena splice variants are suppressed by theinhibitor of Mena. In an embodiment, all Mena splice variants aresuppressed by the inhibitor of Mena. This is effective since Mena istetrameric and can be partially functional even when only a subset ofisoforms are expressed (Eddy et al 2017).

A method of reducing chemotherapy-induced metastasis, orchemotherapy-induced cancer cell dissemination, is provided comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of a Tie-2 inhibitor effective to reducechemotherapy-induced metastasis or chemotherapy-induced cancer celldissemination.

In an embodiment, the Tie-2 inhibitor is rebastinib(4-[4-[(5-tert-butyl-2-quinolin-6-ylpyrazol-3-yl)carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide).

In an embodiment of the methods, the patient has a localized cancertreated with neoadjuvant chemotherapy. In an embodiment, the patient hasmetastatic disease treated with chemotherapy.

In an embodiment of the methods, the chemotherapy is an anti-tubulinchemotherapy.

In an embodiment of the methods, the chemotherapy comprisesadministering a taxane.

In an embodiment of the methods, the chemotherapy comprisesadministering paclitaxel or eribulin.

In an embodiment of the methods, the cancer is a breast cancer.

In an embodiment of the methods, the breast cancer is an adenocarcinoma.

In an embodiment of the methods, the breast cancer is Human EpidermalGrowth Factor 2 Negative. In an embodiment, the breast cancer isestrogen and/or progesterone hormone receptor positive. In anembodiment, the breast cancer is Her2/Neu positive. In an embodiment,the breast cancer is triple negative. In an embodiment, the breastcancer is estrogen and/or progesterone positive/Her2Neu positive.

In an embodiment of the methods, the breast cancer is a recurrent breastcarcinoma.

In an embodiment of the methods, the breast cancer is localized breastcancer (stages I-III). In an embodiment, the breast cancer is metastaticdisease (stage IV). In an embodiment, the breast cancer is carcinoma insitu (stage 0).

In an embodiment of the methods, the chemotherapy is a neoadjuvanttherapy.

In an embodiment of the methods, the metastasis is a lung metastasis,bone metastasis, lymph node metastasis, liver metastasis or brainmetastasis. In an embodiment, the metastasis is any recurrence of thedisease in a distant site including, but not limited to, lung, bone,lymph node, liver or brain.

In an embodiment of the methods, the method is for reducingchemotherapy-induced metastasis.

In an embodiment of the methods, the method is for reducingchemotherapy-induced cancer cell dissemination.

Also provided is a method of reducing chemotherapy-induced tumormicroenvironment of metastasis (TMEM) activity in a patient comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of a Tie-2 inhibitor effective to reducechemotherapy-induced TMEM activity.

In an embodiment, the Tie-2 inhibitor is rebastinib(4-[4-[(5-tert-butyl-2-quinolin-6-ylpyrazol-3-yl)carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide).

In an embodiment of the methods, the patient has a localized cancertreated with neoadjuvant chemotherapy. In an embodiment, the patient hasmetastatic disease treated with chemotherapy.

In an embodiment of the methods, the chemotherapy is a neoadjuvanttherapy.

In an embodiment of the methods, the chemotherapy is a taxane (e.g.paclitaxel), a non-taxane microtubule inhibitors (e.g. eribulin), atopoisomerase inhibitor (e.g. etoposide), an intercalating agent (e.g.doxorubicin), a DNA cross-linking agent (e.g. cisplatin), an alkylatingagent (e.g. cyclophosphamide). In an embodiment, the chemotherapy is acombination of two or more of said chemotherapies.

In an embodiment of the methods, the chemotherapy is an anti-tubulinchemotherapy.

In an embodiment of the methods, the chemotherapy comprisesadministering a taxane.

In an embodiment of the methods, the chemotherapy comprisesadministering paclitaxel or eribulin.

In an embodiment of the methods, the neoadjuvant therapy comprisesdoxorubicin and cyclophosphamide.

In an embodiment of the methods, the cancer is a breast cancer.

In an embodiment of the methods, the breast cancer is an adenocarcinoma.

In an embodiment of the methods, the breast cancer is Human EpidermalGrowth Factor 2 Negative. In an embodiment, the breast cancer isestrogen and/or progesterone hormone receptor positive. In anembodiment, the breast cancer is Her2/Neu positive. In an embodiment,the breast cancer is triple negative. In an embodiment, the breastcancer is estrogen and/or progesterone positive/Her2Neu positive.

In an embodiment, the breast cancer is a recurrent breast carcinoma.

In an embodiment, the breast cancer is localized breast cancer (stagesI-III). In an embodiment, the breast cancer is metastatic disease (stageIV). In an embodiment, the breast cancer is carcinoma in situ (stage 0).

Also provided is a method of inhibiting metastasis of a cancercomprising administering, to a patient with a cancer, an amount of aTie-2 inhibitor effective to inhibit metastasis of a cancer.

In an embodiment, the Tie-2 inhibitor is rebastinib(4-[4-[(5-tert-butyl-2-quinolin-6-ylpyrazol-3-yl)carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide).

In an embodiment, the cancer is a breast cancer.

In an embodiment, the breast cancer is an adenocarcinoma.

In an embodiment, the breast cancer is Human Epidermal Growth Factor 2Negative.

In an embodiment, the breast cancer is a recurrent breast carcinoma.

In an embodiment, the breast cancer is a Stage IV breast cancer.

In an embodiment of the methods, the patient is a human patient.

A metastasis is the existence or development, in a subject with aprimary site of cancer, of one or more secondary malignant growths at adistance from the primary site of cancer.

Reducing chemotherapy-induced metastasis means impairing the developmentof, or reducing the extent of, chemotherapy-induced metastasis(metastasis associated with chemotherapy treatment(s)).

A cancer cell dissemination is the movement of one or more cancer cellsaway from the site of the cancer.

Reducing chemotherapy-induced cancer cell dissemination means impairingthe development of, or reducing the extent of, chemotherapy-inducedcancer cell dissemination (cancer cell dissemination associated withchemotherapy treatment(s)).

As used herein a “tumor” is a detectable malignant tumor usuallypresenting as a lesion or lump located in an organ or tissue in asubject, or in adjacent organs and or tissues in a subject.

In an embodiment, the composition is a pharmaceutical composition. In anembodiment, the pharmaceutical composition comprises a pharmaceuticallyacceptable carrier. As used herein, “pharmaceutically acceptablecarrier” or “pharmaceutical acceptable excipient” includes any materialwhich, when combined with an active ingredient, allows the ingredient toretain biological activity and is non-reactive with the subject's immunesystem. Examples include, but are not limited to, any of the standardpharmaceutical carriers such as a phosphate buffered saline solution,water, emulsions such as oil/water emulsion, and various types ofwetting agents. Preferred diluents for aerosol or parenteraladministration are phosphate buffered saline (PBS) or normal (0.9%)saline. Compositions comprising such carriers are formulated by wellknown conventional methods (see, for example, Remington's PharmaceuticalSciences, 18th edition, A. Gennaro, ed., Mack Publishing Co., Easton,Pa., 1990; and Remington, The Science and Practice of Pharmacy 20th Ed.Mack Publishing, 2000).

A method for identifying a subject as likely having a poor long-termresponse to chemotherapy comprising determining, in a sample obtainedfrom the subject, the level of Mena^(Calc), Mena^(INV) or a TMEM scorethereof, and comparing to a predetermined control level of Mena^(Calc),Mena^(INV) or TMEM score, respectively, and identifying the subject ashaving a poor long-term response to chemotherapy wherein a subject isidentified as likely having a poor long-term response to chemotherapywhen the sample obtained from the subject has a level of Mena^(Calc),Mena^(INV) or TMEM score above the predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively. In an embodiment, apoor long-term response to chemotherapy means the subject willexperience distant recurrence of disease subsequent to the chemotherapy.In an embodiment chemotherapy as used in regard to this method means acytotoxic chemotherapy in clinical use including taxanes (e.g.paclitaxel), non-taxane microtubule inhibitors (e.g. eribulin),topoisomerase inhibitors (e.g. etoposide), intercalating agents (e.g.doxorubicin), DNA cross-linking agents (e.g. cisplatin), alkylatingagents (e.g. cyclophosphamide) or combinations of these. In anembodiment, the sample is a tumor sample. Mena^(Calc) is calculated astotal amount of Mena minus total amount of Mena11a in a region ofinterest or a sample.

A method for identifying a subject as likely having a tumor resistant toa receptor tyrosine kinase (RTK) inhibitor therapy comprisingdetermining, in a sample of the tumor obtained from the subject, thelevel of Mena^(Calc), Mena^(INV) or a TMEM score thereof, and comparingto a predetermined control level of Mena^(Calc), Mena^(INV) or TMEMscore, respectively, and identifying the subject as having a tumorresistant to RTK inhibitor therapy, wherein a subject is identified aslikely having a tumor resistant to RTK inhibitor therapy when the sampleobtained from the subject has a level of Mena^(Calc), Mena^(INV) or TMEMscore above the predetermined control level of Mena^(Calc), Mena^(INV)or TMEM score, respectively. In an embodiment, the RTK inhibitor therapycomprises a EGFR, HGFR, IGFR, CSF1R, VEGFR or TK (Src, Abl, Arg)inhibitor. In an embodiment, resistance is dissemination of tumor cellsto distant sites in the presence of the RTK inhibitor. This resistancemay be associated with distant metastasis at a later time.

A method for identifying a subject as likely having a tumor resistant toa receptor tyrosine kinase (RTK) inhibitor and cytotoxic chemotherapycombination therapy comprising determining, in a sample of the tumorobtained from the subject, the level of Mena^(Calc), Mena^(INV) or aTMEM score thereof, and comparing to a predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively, and identifying thesubject as having a tumor resistant to RTK inhibitor and cytotoxicchemotherapy combination therapy, wherein a subject is identified aslikely having a tumor resistant to RTK inhibitor therapy and cytotoxicchemotherapy combination therapy when the sample obtained from thesubject has a level of Mena^(Calc), Mena^(INV) or TMEM score above thepredetermined control level of Mena^(Calc), Mena^(INV) or TMEM score,respectively. In an embodiment, the resistance is dissemination ofcancer cells to distant sites and/or lack of decrease in tumor sizeand/or continuous tumor growth at primary and distant sites in presenceof the drugs. This resistance may be associated with distant metastasisat a later time.

Mena^(INV) expression in tumor cells resulting from macrophage contactincreases sensitivity of RTKs (EGFR, HGFR, IGFR, CSF1R) to their ligandsand resistance of tumor cells to RTK (EGFR, HGFR, IGFR, CSF1R, Tie2,VEGFR) and TK (Src, Abl, Arg) inhibitors. Resistance is defined ascontinued signaling to ligands of these RTKs and upstream pathwaysignals to TKs resulting in cancer cell dissemination to distant sitesand lack of growth inhibition and/or continued growth at primary anddistant sites. This resistance may be associated with distant metastasisat a later time. Resistance here is applicable to estrogen and/orprogesterone hormone receptor positive, Her2/Neu positive and triplenegative subtypes of breast cancer. Resistance as used herein isapplicable to all stages of invasive disease; i.e. localized breastcancer (stages I-III) and metastatic disease (stage IV), as well ascarcinoma in situ.

All combinations of the various elements described herein are within thescope of the invention unless otherwise indicated herein or otherwiseclearly contradicted by context.

This invention will be better understood from the Experimental Details,which follow. However, one skilled in the art will readily appreciatethat the specific methods and results discussed are merely illustrativeof the invention as described more fully in the claims that followthereafter.

EXPERIMENTAL DETAILS Introduction

The inventors hypothesized that preoperative chemotherapy might increasethe density and the activity of TMEM sites as well as expression ofinvasion promoting Mena isoforms within the primary tumor andconsequently induce cancer cell dissemination and distant metastasiswhile at the same time reducing cancer burden. Such a side effect woulddiminish the clinical benefit of NAC. If this was the case, it mightalso be possible that this effect could be blocked by inhibitors of TMEMfunction. Herein, the inventors tested this hypothesis by using fixedtissue and intravital imaging of PyMT murine models and patient-derivedxenografts, as well as pre- and post-NAC (paclitaxel followed bydoxorubicin plus cyclophosphamide) breast cancer tissue samples fromhuman patients.

Results

Paclitaxel Delays Tumor Growth but Increases TMEM Assembly in BreastCancer: Chemotherapy induces recruitment of endothelial progenitors andTie2⁺ monocyte progenitors into the tumor (10, 11, 30), and thislaboratory has previously demonstrated that Tie2^(hi) macrophages arerequired for TMEM-mediated cancer cell intravastaion (1). Herein, thepossibility was examined that neoadjuvant paclitaxel promotes TMEMassembly and cancer cell dissemination and metastasis. This hypothesiswas investigated in the following breast carcinoma models: (i)transgenic MMTV-PyMT mice bearing spontaneous breast tumors, (ii) FVBmice transplanted orthotopically with tumors from MMTV-PyMT donors, and(iii) two patient-derived xenografts (PDX), HT17 and HT33, developedpreviously in our laboratory (31). Animals were treated with 10 mg/Kgpaclitaxel every five days, three times in total, as shown in FIG. A,and upon sacrifice, tumor growth, Tie2 macrophage recruitment and TMEMassembly were evaluated. Treatment of all groups began at the earlycarcinoma stage (tumor size of ˜0.3 cm) when there is minimal or absentnecrosis. It was decided to work with the early-stage PyMT mouse mammarycarcinoma model because it more accurately reflects clinically relevantscenarios where most women present with small tumors of <2 cm (32). Atthe end of treatment all tumors were histologically classified asinvasive carcinomas. Although paclitaxel-treated tumors showed delayedtumor growth, they revealed 2- to 3-fold higher TMEM score (p<0.001)compared to non-treated controls in all the experimental models tested(FIG. 1B).

Paclitaxel Increases the Infiltration of PerivascularTie2^(hi)/Vegf^(hi) Macrophages in the Primary Breast CancerMicroenvironment—To explain the mechanism of increased TMEM assemblyupon administering chemotherapy in breast tumors, we investigated ifpaclitaxel affects intratumoral macrophage density, as previouslysuggested (33). A significant increase (p<0.01) was found in thepercentage of macrophage-specific Iba1⁺ area in paclitaxel-treated micein all transplantation models, except in the PyMT-spontaneous model. Theabsolute number of Iba1⁺ cells was also significantly increased(p<0.001) in the paclitaxel-treated HT17-xenograft but not in thePyMT-spontaneous model, when quantified either over the entire tissue,or only in the perivascular niche, where TMEM structures are located(FIG. 1C).

The functional TMEM sites contain Tie2^(hi)/Vegf^(hi) macrophages andinvasive tumor cells in perivascular regions (1), and it wasindependently shown that chemotherapy may promote mobilization of suchTie2^(hi) monocyte progenitors in primary tumors (8, 10). TheTie2^(hi)/Vegf^(hi) macrophage subpopulation was quantified herein usingmulti-channel immunofluorescence (IF) imaging (FIGS. 1D-F) (10, 14, 34).FIG. 1E illustrates a representative IF image of a Tie2^(hi)/Vegf^(hi)macrophage quantified using Cd31, Iba1, Vegf and Tie2 staining. FIG. 1Fillustrates representative examples of Vegf^(hi) and Vegh^(lo)macrophages as seen comparatively in the same fields of view, bycombining Cd31, Iba1 and Vegf staining. Upon quantification,paclitaxel-treated mice had significantly higher (p<0.001) density ofTie2^(hi)/Vegf^(hi) macrophages compared to the vehicle-treatedcontrols, regardless of whether these were assessed in the entire tissueor only in the perivascular niches (FIG. 1D). The proportion ofTie2^(hi)/Vegf^(hi) macrophages among all Iba1⁺ cells was also increasedby paclitaxel treatment. Importantly, the significant increase of theperivascular Tie2^(hi)/Vegf^(hi) macrophage subpopulation was alsodemonstrated in the PyMT-spontaneous model (FIG. 1D), indicating asignificant change in macrophage population dynamics in preference ofTie2⁺ upon paclitaxel treatment.

In the PyMT-spontaneous model, the total Iba1⁺ macrophage countscorrelated very poorly with TMEM score (FIG. 1G, left panel), but wefound comparatively stronger correlations (p<0.001) of TMEM withperivascular Tie2^(hi)/Vegf^(hi) macrophages (R²=0.5) (FIG. 1G, rightpanel). In the HT17-xenograft, both total Iba1⁺ macrophages (FIG. 1H,left panel) and perivascular Tie2^(hi)/Vegf^(hi) macrophages (FIG. 1H,right panel) correlated equally well (R²=0.65 and R²=0.55, respectively)with TMEM score (p<0.001, in both cases). Both TMEM score values andperivascular Tie2^(hi)/Vegf^(hi) macrophages remained significantlyincreased upon chemotherapy treatment, even after their values werenormalized to microvascular density. Collectively, these data indicatethat at least in the case of PyMT-spontaneous tumors, the increased TMEMassembly after paclitaxel treatment does not necessarily occur due torandom spatial juxtaposition of tumor-associated vasculature withinfiltrating macrophages, but is specifically associated with therecruitment of Tie2^(hi)/Vegf^(hi) macrophages in the perivascularniche. In conclusion, neoadjuvant paclitaxel specifically promotes theassembly of TMEM sites containing the Tie2^(hi)/Vegf^(hi) macrophagethat is required for TMEM activity in primary breast cancer.

Paclitaxel Induces TMEM-Dependent Vascular Permeability in BreastTumors—Given that chemotherapy treatment may affect blood vesseldynamics by inducing angiogenesis (9, 11-13, 35-37), intravital imaging(IVI) (FIG. 2A) was used to investigate whether neoadjuvant paclitaxelinduces TMEM-dependent (localized) or TMEM-independent (more universal)blood vessel leakage. Tumors in mice treated with paclitaxel did notdemonstrate generalized blood vessel leakage of 155-KDa dextran into theextravascular space. Instead, they showed localized areas of transientvascular permeability called “bursting” (FIG. 2B, similar to thoseobserved previously in untreated tumors (1). In particular, FIG. 2Billustrates a characteristic example of peak bursting activity (stillimage on the left of FIG. 2B) on a TMEM site, though not all TMEMpresented with bursting activity (still image on the right of FIG. 2B);bursting was not captured for all observed TMEM sites. Importantly, allthe “bursting” incidents occurred only at TMEM sites, i.e. in closeproximity to at least one Dendra2⁺ tumor cell and one CFP⁺ macrophage(FIG. 2B, left image). As also reported previously (1), we neverobserved any bursting incidents without juxtaposition to a clearlydefined TMEM site. Bursting was documented by the accumulation ofDextran-TMR signal over time around an active TMEM site, and no suchaccumulation was observed away from TMEM (FIGS. 2B-C). The entiretime-lapse of these was recorded in videos, respectively. The intensityvalues from all TMEM-mediated bursting incidents observed inpaclitaxel-treated mice were averaged and plotted over the entire timeof bursting activity (FIG. 2D), which confirmed the transient nature ofpaclitaxel-induced TMEM-dependent vascular permeability. In conclusion,chemotherapy treatment in early-stage PyMT tumors was able torecapitulate bursting similar to the one observed in untreated,late-stage PyMT tumors (1).

To explicitly demonstrate that tumor cell intravasation after paclitaxeltreatment is dependent on TMEM-dependent bursting, we measured the tumorcell-specific Dendra2 signal intensity in blood vessel ROIs that weredirectly juxtaposed to or away from bursting (FIG. 2C). Signal intensityof Dextran-TMR was also quantified in the corresponding extravascularROIs for purposes of confirming the presence of bursting. It was foundthat cancer cell intravasation in paclitaxel-treated animals occursduring or shortly after the bursting event, specifically at TMEM sitesassociated with bursting, but never before the bursting event, or at theTMEM sites without bursting activity (FIG. 2C).

In a second independent validation experiment, a group of vehicle- orpaclitaxel-treated mice received an i.v injection of Dextran-TMR for 1hour and then sacrificed and evaluated for vascular permeability infixed tumor sections (FIG. 2A). Multichannel IF staining includedendomucin as a blood vessel exclusion mask and a specific anti-TMRantibody for assessing dextran leakage. A corresponding TMEM IHCstaining section was co-aligned to evaluate the presence/absence of TMEMin each vascular profile that presented with vascular leakage. Twoexamples of vascular profiles selected from a paclitaxel-treated mouseare demonstrated in FIG. 2E; the upper row shows a vascular profile withabundant extravascular dextran which co-localized with 2 TMEM sites,while the lower row shows a vascular profile with absent or minimalextravascular dextran which co-localized with a blood vessel lackingTMEM (FIG. 2E). For quantification purposes, ˜20-30 vascular profileswere selected for each mouse, based on tissue size, degree ofvascularization and quality of endomucin staining. In bothvehicle-treated and paclitaxel-treated groups, approximately 96-98% ofthe vascular profiles with extravascular dextran co-localized with atleast 1 TMEM (FIG. 2F).

Paclitaxel Increases Metastatic Dissemination of Breast Tumors—To assessif paclitaxel treatment promotes tumor cell dissemination and metastaticincidence, we first quantified and compared incidence and frequency ofbursting in mice treated with vehicle or paclitaxel, using IVI (FIGS.3A-C). The incidence (at least 1 bursting event in a ˜4.5-hour imagingsession) and frequency of bursting were increased in mice treated withpaclitaxel, when compared to those treated with vehicle control (FIGS.3B-C). The same conclusions were reached when frequency of bursting wasnormalized to the number of TMEM sites, as measured in each field.Unlike in late-stage tumors in which TMEM show spontaneous activity,TMEM-associated bursting is a very rare phenomenon in early carcinoma(FIG. 3C) as we have already reported (1). However, TMEM-associatedbursting can be induced by chemotherapy. In addition to IVI,extravascular dextran area was quantified and compared as % normalizedto the blood vessel area in fixed tumors of mice treated with eithervehicle or paclitaxel, using multichannel IF. Extravascular dextran was3-fold (p<0.05) more abundant in paclitaxel-treated compared tovehicle-treated mice (FIGS. 3D-E). Since we have demonstrated thatbursting (as visualized through IVI) and extravascular dextran (asquantified in fixed-tissue IF), are both associated with TMEM (FIG. 2),the data presented in FIGS. 3A-E collectively demonstrate thatpaclitaxel-treated tumors have increased TMEM-mediated vascularpermeability compared to non-treated controls.

Having shown that TMEM function is additionally associated withtumor-cell intravasation in chemotherapy-treated tumors (FIG. 2C) as inthe case of non-treated tumors (1), it was then asked whether paclitaxeltreatment induces increased metastatic dissemination of breast cancercells. An at least 2-fold increase was found in circulating tumor cells(CTCs) (p<0.05) following paclitaxel treatment in all experimentalmodels examined (FIG. 3F). TMEM score and CTCs correlated positively inthe PyMT-spontaneous (R²=0.57, p<0.001), the PyMT-transplantation(R²=0.63, p<0.001), as well as in both patient-derived xenograft (PDX)models, the HT17 (R²=0.28, p<0.05) and the HT33 (R²=0.28, p<0.05),though correlations were weaker in the latter models (FIG. 3G). SinceSCID mice used in the latter models are engineered to lose theiradaptive but to retain their innate immunity, it is possible that theweaker correlations were due to a differential degree of immune-mediatedrejection of CTCs.

To further determine the effect of paclitaxel on cancer celldissemination to distant sites, we harvested lungs and evaluatedmetastatic foci histologically. An increase was found in both themetastatic incidence (>1 micrometastatic focus of >5 tumor cells) (FIG.3H) and the number of cancer cell micrometastases in the lungs ofpaclitaxel-treated mice (FIG. 3I). In addition, we quantified singlecell dissemination of breast cancer cells in the lungs of FVB-recipientmice after syngeneic transplantation of MMTV-PyMT/Dendra2+ tumors usingex vivo microscopy, and found an approximately 2-fold increase (p<0.01)of single Dendra2+ breast cancer cells in the lungs ofpaclitaxel-treated mice (FIG. 3J). Overall, data presented in thissection indicate that in early-stage breast cancers chemotherapyincreases vascular permeability at TMEM sites which is accompanied byincreased cancer cell dissemination.

Paclitaxel Promotes the Expression of Invasive Isoforms of Mena inBreast Tumors—Since the data show that paclitaxel treatment increasesTMEM assembly, as well as TMEM-dependent vascular permeability andmetastatic dissemination, we hypothesized that it also increases theproportion of highly migratory cancer cells, known to express invasiveisoforms of the actin-regulatory protein Mena (20, 22), capable ofassembling and using TMEM sites to intravasate, which is one of themajor prerequisites for successful metastatic seeding. To test thishypothesis, qRT-PCR analysis was first performed for total Mena(panMena), Mena11a and Mena^(INV) on formalin-fixed paraffin-embedded(FFPE) tumors from all mouse models. Paclitaxel treatment significantlyincreased (p<0.01) the expression of PanMena (defined as all Menaisoforms), Mena^(INV), and Mena^(Calc), a marker that takes into accountthe full repertoire of invasive Mena isoforms including Mena^(INV)(38,39), but not that of the anti-metastatic Mena11a (FIG. 4A-D), andcorrelates with distant recurrence in breast patients (38, 39). Inaddition, both Mena^(Calc) and Mena^(INV) correlated positively withincreased TMEM score (Mena^(INV), p<0.001; Mena^(Calc), p<0.01) in bothmodels tested (FIG. 4E), with Mena^(INV) demonstrating highercorrelation coefficients than Mena^(Calc) (Mena^(Calc) 0.36 versusMena^(INV) 0.61 for PyMT-spontaneous, and Mena^(Calc) 0.56 versusMena^(INV) 0.72 for HT17-xenograft). Paclitaxel-mediated Mena^(INV)increased expression (p<0.0001) and correlation with TMEM score(p<0.001) were also confirmed at the protein level in both thePyMT-spontaneous and the HT17-xenograft models (FIGS. 4F-G). As shown inthe specific Mena^(INV) IF, the pattern of Mena^(INV) expression in PyMTmice was heterogeneous (FIG. 4F), consistent with previous observations(40). Interestingly, we found a positive correlation betweenTie2^(hi)/Vegf^(hi) macrophage infiltration and Mena^(INV) expression(p<0.0001, R²=0.68), as well as Mena^(Calc) (p<0.05, R²=0.24),supporting our recently reported evidence that direct contact of tumorcells with macrophages induces Mena^(INV) expression (27). In addition,there was an inverse correlation for the anti-metastatic Mena11a(p<0.01, R²=−0.3).

Paclitaxel Promotes Breast Cancer Cell Dissemination in a Mena-DependentManner—previous work has demonstrated that animals grafted withMMTV-PyMT Mena-null tumors do not develop circulating tumor cells andlung metastases (28), indicating that Mena is necessary for tumor celldissemination. Having shown that paclitaxel increases TMEM assembly(FIG. 1B) and invasive Mena isoform expression (FIGS. 4C-D and FIG.4F-G), we next investigated if paclitaxel-mediated tumor celldissemination in invasive breast cancer was also Mena-dependent. To testthis hypothesis, we orthotopically transplanted Mena^(−/−) or Mena^(+/+)CFP-fluorescent PyMT-tumors into wild-type syngeneic hosts to assesstumor cell intravasation and dissemination in the lungs of mice afterpaclitaxel treatment (FIG. 5A). Mena^(−/−) mice did not expressMena^(INV) at the protein level. Quantitative assessment of macrophagesin the perivascular niches of Mena mice revealed both increased Iba1⁺and Tie2^(hi)/Vegf^(hi) Iba1⁺ macrophage infiltration after paclitaxeltreatment (FIG. 5B-E), similar to changes observed in PyMT and HT17Mena^(+/+) mice after receiving chemotherapy (FIG. 1C-D). These resultsindicate that Mena is not necessary for paclitaxel mediatedTie2^(hi)/Vegf^(hi) macrophage recruitment in the primary breast tumormicroenvironment (FIG. 5B).

Since a Mena-expressing tumor cell constitutes one of the elements ofthe tripartite TMEM structure, Mena-null tumors do not assemble TMEM.However, since the perivascular Tie2^(hi)/Vegf^(hi) macrophages could berecruited by paclitaxel treatment even in the Mena-null tumors (FIGS.5D-E), it was next investigated whether these Tie2^(hi)/Vegf^(hi)macrophages were by themselves sufficient to cause increased cancer celldissemination, without the presence of a complete TMEM structure.However, the absence of the Mena gene completely eliminated CTCs(p<0.0001) and the number of single cancer cells disseminating in thelungs (p<0.0001) (FIG. 5F-G), as has also been previously shown (28).This suppression was consistent regardless of vehicle or paclitaxeltreatment (FIGS. 5F-G), indicating that the elimination of the Mena genein breast cancers affects cancer cell intravasation and dissemination,even though it still permits the paclitaxel-mediated increase ofperivascular Tie2^(hi)/Vegf^(hi) macrophages. Thus, paclitaxel treatmentin Mena PyMT-CFP transplants failed to boost the number of CTCs in theblood or disseminated cells in the lungs, as seen in the case ofMena^(+/+) mice (FIGS. 5F-G). In summary, these data show thatpaclitaxel-induced tumor cell dissemination is also dependent on Menaexpression, further supporting the essential role of TMEM in paclitaxeltumor cell dissemination. Blocking expression or function of Mena istherefore very valuable therapeutically.

Doxorubicin/Cyclophosphamide Treatment Elicits Similar-to-PaclitaxelPro-metastatic Changes in the Breast Cancer Microenvironment—Havingshown that paclitaxel induces TMEM- and Mena-mediated pro-metastaticchanges in the primary breast tumor microenvironment in a wide varietyof mouse models, we then examined whether similar effects could beelicited by other chemotherapeutics. Doxorubicin/cyclophosphamidecombinatorial chemotherapy was selected because it is a main componentof neoadjuvant chemotherapy in human breast cancer patients (41, 42).Transgenic MMTV-PyMT mice bearing spontaneous breast tumors received atotal of three doses of 5 mg/Kg doxorubicin i.v. every five days and 1single dose of 120 mg/Kg cyclophosphamide i.p., as illustrated in FIG.6A. Upon histological examination of the resulting tumors, necrosis andcell death were more evident in the doxorubicin/cyclophosphamide-treatedtumors when compared to vehicle-treated mice (FIG. 6B). TMEM score wassignificantly (p<0.05) increased after doxorubicin/cyclophosphamidetreatment (FIG. 6B-C), and was accompanied by a significant ˜1.3-foldelevation in the number of circulating tumor cells (FIG. 6D), as well asincreased numbers of perivascular Tie2^(hi)/Vegf^(hi) macrophagescompared to vehicle-treated controls (FIG. 6E). Therefore,doxorubicin/cyclophosphamide affects TMEM density, TMEM activity andCTCs in a similar fashion as paclitaxel treatment, further indicatingthat similar pro-metastatic effects may be elicited by a variety ofneoadjuvant chemotherapy (NAC) regimes.

Neoadjuvant Chemotherapy with Paclitaxel Inclusion InducesPro-metastatic Changes in the Tumor Microenvironment of Human BreastCancer Patients—the investigations were expanded to human breast cancerpatients. The change in TMEM density in post-NAC specimens was evaluatedin 20 patients with ER⁺/Her2⁻ disease, treated with weekly paclitaxelfor up to 12 weeks followed by 4 cycles of doxorubicin pluscyclophosphamide, and had residual disease after NAC (residual cancerburden [RCB] score 2-3). None of the patients received pre-operativeTamoxifen. When TMEM scores were graphed for each patient individually(FIG. 7A) the following observations were made: (I) an increase in TMEMscore following NAC was observed in most patients, with a fewrepresenting notable fold-changes of >5 (e.g. patients #3, #11, #15, #19and #20), (II) TMEM score from 50% of patients moved fromlow/intermediate into high-risk group (score of 23; red line in thegraph) following NAC. TMEM score above 23 was established as the cutoffthat separates patients into low/intermediate and high risk groups fordeveloping distant metastasis (5), (III) in 15% of patients with alreadyhigh TMEM score before the beginning of NAC, TMEM score remainedunaltered or even worsened by the end of the treatment (e.g. patients#4, #9 and #17), (IV) there was not a single patient that demonstrated adecrease in TMEM score following NAC. Representative images of TMEMbefore and after NAC are shown for patients #3 and #7 (FIG. 7B). Whenanalyzed as a cohort, the mean TMEM score was significantly increased(Wilcoxon test; p<0.0001) in post-NAC samples compared to pre-NAC corebiopsies (FIG. 7C). These data suggest that NAC may have unwanted longterm consequences in a certain subgroup of breast cancer patients.

To further substantiate the translational importance of our preclinicaldata from PyMT and PDX mice receiving neoadjuvant paclitaxel into humanbreast cancer patients, we compared Mena^(INV) expression levels in Pre-and Post-NAC samples. We observed a significant increase (p<0.01) inMena^(INV)-positive area between pre-NAC biopsies and post-NAC tumors(FIGS. 7D-E). Additionally, we analyzed Mena^(INV) expression by qRT-PCRin fine needle aspiration (FNA) biopsies taken before and one week afterthe second dose of weekly paclitaxel in an independent small cohort ofpatients (n=5). Even at such an early phase of paclitaxel treatment, wewere able to observe an increase of Mena^(INV) gene-expression in 4/5breast cancer patients (Patients #1 and #3-5) (FIG. 7F), suggesting thatthe TMEM- and Mena-dependent pro-metastatic changes may have alreadybeen initiated in these patients.

Inhibition of the Tie2 Receptor Reverses the Paclitaxel-MediatedPro-metastatic Changes—It was postulated that selective Tie2 inhibitorscould not only be successfully used to counteract the angiogenicpotential of NAC-induced endothelial progenitor cell infiltration aspreviously documented (9, 12, 13, 35, 36), but also the TMEM- andMena-dependent pro-metastatic changes described in the current work,given that Tie2 inhibitors could additionally target TMEM-associatedTie2^(hi)/Vefg^(hi) macrophages.

To address this question, the effects of rebastinib, a selectiveTie2-inhibitor, were first investigated on TMEM assembly, vascularpermeability and circulating tumor cells in the PyMT-transplantation andHT17 patient-derived xenograft mammary tumor cohorts used in ourstudies. Animals received chemotherapy with or without rebastinib asshown in FIG. 8A. Treatment with rebastinib alone did not significantlyaffect the overall TMEM score (FIG. 8B-C), or the density ofperivascular Tie2^(hi)/Vegf^(hi) macrophages (FIGS. 8D-E). However, itsignificantly (p<0.01) reduced the number of CTCs in both animal models(FIGS. 8F-G), thus significantly impairing hematogenous dissemination,without affecting the assembly of TMEM intravasation sites, indicatinginhibition of TMEM activity.

Treatment with paclitaxel-only led to a significant increases inperivascular Tie2^(hi)/Vegf^(hi) macrophages, TMEM assembly and activityas has been observed in all our earlier experiments (compare: FIG. 8B/Cwith 1B; FIG. 8D/E with 1D; FIG. 8F/G with 3F). More importantly,administration of rebastinib in paclitaxel-treated animals decreased thenumber of perivascular Tie2^(hi)/Vegf^(hi) macrophages (FIG. 8D) anddecreased circulating tumor cells to the level observed in the controlanimals (FIGS. 8F-G) without affecting TMEM assembly (FIGS. 8B-C). Thesedata strongly indicate that Tie2 inhibition successfully blocks thefunction, but not the assembly of TMEM sites, which is sufficient tosuppress cancer cell dissemination.

Next investigated was whether rebastinib-mediated suppression of tumorcell dissemination observed in the paclitaxel-treated mice was indeeddue to inhibition of TMEM-associated macrophage function. To addressthis issue, IVI was used (FIG. 8A), and again found that baselineincidence and frequency of bursting, an activity uniquely associatedwith TMEM activity, were identical to the previously acquired data inthe “paclitaxel-only” group (compare: FIGS. 8H-I with 3B-C). However,the co-administration of rebastinib in paclitaxel-treated micecompletely abolished the incidence and frequency of bursting (FIG.8H-I), suggesting that Tie2 inhibition blocks chemotherapy-drivenTMEM-mediated vascular permeability and cancer cell dissemination.

DISCUSSION

Accumulating evidence indicates that chemotherapy evokes a host-repairresponse, during which bone marrow-derived cells (BMDCs) infiltrate theprimary tumor microenvironment and facilitate neo-angiogenesis and tumorregrowth (10, 11). Herein it is shown that through such BMDCrecruitment, NAC may increase cancer cell dissemination and induce amore aggressive tumor phenotype leading to increased metastasis. Theexact mechanism involves both the assembly of TMEM sites and theincreased Mena^(INV) expression in residual cancer after NAC. Theseresults are consistent with our previous findings that Mena expressionis required for TMEM assembly and for cancer cell dissemination througha TMEM, Mena^(INV) and Tie2^(hi)/Vegf^(hi)-macrophage-dependentmechanism (1, 19, 20, 29). It should be noted that although the effectsof taxanes and other chemotherapeutics on neovascularization have beenadequately described (8, 10, 12, 13, 35, 44), our study provides insighton the mechanisms by which paclitaxel and other chemotherapy modulatesthe cancer microenvironment to promote breast cancer cell intravasation,and cancer cell dissemination to distant sites, as well as aTie2-directed therapeutic approach to counteract paclitaxel-mediatedinduction of cancer cell dissemination (FIG. 8J). Thus, this work isprimarily focused on the chemotherapy effect on cancer celldissemination via TMEM/Mena-mediated mechanism, not on the developmentof clinically detectable metastases which involves other processes suchas release from dormancy and tumor growth in addition to cancer celldissemination.

It was demonstrated that chemotherapy increases macrophage density inPDX model, but not in spontaneous PyMT. Our findings in PyMT model arein discrepancy with Coussens group (45). This may be because of the useof 8-9-week old mice bearing early-stage spontaneous carcinomas, whilethe Coussens group worked with 12-week old mice which typically haveadvanced-stage tumors. However, our findings demonstrated thatchemotherapy promotes an increase in perivascular Tie2^(hi)/Vegf^(hi)macrophages (FIG. 8J), which is consistent with studies showing thatthis population associates with sites of (patho)physiologicalangiogenesis, especially as a host-repair mechanism following cytotoxicdamage through chemotherapy (14, 15, 46-48). Although it is not clear ifTie2^(hi)/Vegf^(hi) macrophages belong to the “classically activated”(M1) or “alternatively activated” (M2), they are crucial for modulatingtumor microenvironment in response to cytotoxic therapies (10, 49). Ourobservation that other chemotherapeutics, i.e.doxorubicin/cyclophosphamide, are capable of perivascularTie2^(hi)/Vegf^(hi) macrophage recruitment, TMEM-assembly andTMEM-dependent tumor cell intravasation as well further supports theidea that the mechanism via which chemotherapy induces thesepro-metastatic effects is a generic host-repair mechanism in response toextensive tissue damage and not a paclitaxel-specific phenomenon. Forinstance, it has been previously shown that Tie2⁺ macrophages alsoexpress the chemokine receptor CXCR4, and that chemotherapy may increasethe expression of the CXCR4 ligand CXCL12 in the primary tumormicroenvironment (10). Therefore, it is very likely that thepro-metastatic Tie2^(hi)/Vegf^(hi) macrophages are recruited through adistinct chemotactic axis in chemotherapy-treated individuals.

In addition, increased macrophage infiltration into tumors uponpaclitaxel treatment increases the contact between tumor cells andmacrophages, which is known to stimulate the expression of Mena^(INV)via Notch pathway activation resulting in increased Mena^(INV) andTMEM-dependent intravasation (27). These observations suggest thatpaclitaxel treatment may have induced Mena^(INV) and Mena^(Calc)expression due to chemotherapy-driven macrophage infiltration, leadingto increased TMEM assembly and function as described here (FIG. 8J), andwhich may be an active process and not simply the result of selectivesurvival of Mena-expressing tumor cells during paclitaxel treatment(50). Otherwise, our data are in agreement with findings from Oudin etal. (2016), who showed significantly increased Mena and Mena^(INV)expression in paclitaxel-treated compared to control MDA-MB-213xenografts (50).

The observed increase in disseminating tumor cells upon chemotherapytreatment as a direct consequence of macrophage contact-inducedMena^(INV) overexpression is supported by two key findings reportedhere. First, Mena^(INV) and Mena^(Calc) expression correlated especiallywell with Tie2^(hi) macrophages, consistent with prior studies in humansand in mice (18, 19, 29). Second, the absence of all Mena isoformscompletely abolished cancer cell dissemination and distant metastasis invivo, regardless of whether those mice received paclitaxel or not, andwithout affecting Tie2^(hi)/Vegf^(hi) macrophage recruitment, indicatingthat Mena expression is an essential prerequisite for paclitaxel-inducedbreast cancer cell transendothelial migration in vivo.

The study indicates that the TMEM score and Mena^(INV) increase inbreast cancer samples from patients treated with NAC includingdoxorubicin, cyclophosphamide and paclitaxel, indicating that TMEM scoreand Mena^(INV) might be used in predicting development of pro-metastaticchanges in primary tumor microenvironment in response to NAC. This issignificant given that many breast cancer patients are being treatedwith NAC which typically lasts about 6 months, and currently there areno markers that predict response to NAC (44). Our data indicate that inpatients who have significant residual cancer burden (RCB) post-NAC,such as those with ER⁺ disease, NAC might be inducing metastases viaTMEM, in spite of inducing partial tumor regression. In particular, only16.5% of patients with ER⁺/Her2− disease achieve pathologic completeresponse, indicating that our findings may apply to most patients withER⁺ disease treated with NAC (51). Interestingly, although addition ofpaclitaxel to NAC increases the percentage of patients with pathologicresponse (pCR) it does not improve the overall survival (6, 7)suggesting that some patients do not draw long term benefit from NAC.Since we showed that after only 2 doses of chemotherapy Mena^(INV)increases in certain patients, we speculate that Mena isoform expressionstatus in FNA biopsy after the first 2 weeks of chemotherapy couldpredict which patients would receive full benefit from NAC and in whichcontinuation of NAC would be harmful. For example, an approach could bedeveloped to routinely assess the levels of Mena^(INV) in FNA samplesafter the 2^(nd) chemotherapeutic dose. If the levels of invasiveisoforms of Mena do not increase, the chemotherapy could be continued toits completion. However, if there is an increase in the invasive Menaisoform levels the chemotherapy could be discontinued and these patientscould be treated with surgery first followed by chemotherapy.

Our cohort of 20 patients with ER⁺ disease had only 5 year follow uptime which is not sufficient to reliably analyze distant recurrence inthis breast cancer subtype because ER⁺ disease often recurs 10 or moreyears after the initial diagnosis (52). However, threeretrospective-prospective analyses of human breast cancer samplesindicate that increased TMEM score is associated with metastatic outcomein patients (3, 5, 53). These studies imply that with the proper followup time the increase in TMEM score upon chemotherapy will translate indistant recurrence in some of the patients. A follow up study is neededto determine with certainty if patients with increase in TMEM score uponNAC indeed develop distant recurrence more often than those withoutincrease in TMEM score. In addition, as discussed above, it is necessaryto determine if we can predict which patients are likely to respond toNAC with increase in Mena^(INV) so that the treatment can be adjustedaccordingly.

To accurately reflect clinically relevant scenarios we primarily usedearly-stage PyMT tumors in our study. As reported by American CancerSociety in “Breast cancer facts and FIGS. 2015-2106” the incidence rateis the highest for tumors <2 cm (70 per 100,000), followed by tumors2-4.9 cm (35 per 100,000) (32). Tumors >5 cm had the incidence rate ofonly 10 per 100,000. Likewise, incidence rate for localized (40-90) andregional (25-40) disease far exceeds the incidence rate for distant(5-11) disease (32). In addition, by selecting early-stage PyMT tumors,measuring potentially TMEM-independent mechanisms of cancer celldissemination that could result from an open-circulation effect havebeen avoided, i.e. upon destruction of the blood vasculature in advancedstage necrotic lesions.

Our findings that paclitaxel induces increase in CTCs (FIG. 3F) isconsistent with recently reported data from patient studies focused onthe effect of chemotherapy on CTCs. Although CTC count measured byFDA-approved CellSearch System is a strong prognostic factor in bothprimary and metastatic breast cancer there is no conclusive evidence inthe literature that chemotherapy significantly reduces CTCs (54). On thecontrary, several reports indicate that CTC counts in post-chemotherapyblood samples increase in some patients and decrease others, do notcorrelate with pathologic complete response and correlate with thedistant-metastasis-free survival (55, 56). Moreover, when CTC searchincluded cells with epithelial-mesenchymal transition marker expression,21% of patients showed increased CTC counts post NAC, while 15% showeddecrease in CTCs counts post NAC (56). Thus our data indicating that NACmay be increasing CTCs in some patients are consistent with currentliterature.

Since metastatic disease is the major cause of cancer-related mortalityand currently incurable, it is critical that we develop strategies toprevent progression of cancer to metastatic stage and to prevent furtherspread from already existing metastatic foci. Therefore, our findingthat chemotherapy, when given in the setting of clinically activedisease, promotes cancer cell dissemination is of major concern.However, our data indicate that strategies can be developed to preventchemotherapy induced TMEM/Mena-mediated cancer cell dissemination andsubsequent metastasis. This can be done either by discontinuing NAC inpatients whose tumors show NAC-induced pro-metastatic changes, or bycombining NAC with agents that block TMEM/Mena-mediated cancer celldissemination, such as selective Tie2 inhibitors (FIG. 8J), which wouldbe useful not only in NAC treatment of localized breast cancer, but alsoin treatment of metastatic breast cancer.

Materials and Methods

Drug Administration. The following drugs were administered in mice:Paclitaxel was given at 10 mg/Kg i.v every 5 days for 2 weeks;Doxorubicin was given at 5 mg/Kg i.v. every 5 days for 2 weeks;Cyclophosphamide was given at 120 mg/Kg i.p. only once; Rebastinib wasgiven at 10 mg/Kg per os, every 3-4 days for 4 weeks.

Animals and Animal Procedures. MMTV-PyMT mice were bred in-house at theAlbert Einstein College of Medicine (AECOM). Generation of MMTV-PyMTMena has been described previously (28). CFP- or Dendra2-labeled mammarycarcinoma cells were generated on the FVB background by co-injection ofTg(MMTV-iCRE)1jwp together with Tg(PCAG-loxp-CATstop-loxp-CFP) orTg(loxP-stop-loxP-PDendra2)jwp plasmids, respectively, by conventionalmethods in the Albert Einstein Transgenic Mouse Facility. All syngeneictransplantation models were generated through orthotopic transplantationof 1 mm×1 mm tumor chunks, using tumors of cm-diameter from 12-16-weekold MMTV-PyMT mena−/− or mena+/+ donor mice into 5-6 week-old FVBrecipients. Tumor chunks were implanted on the fourth mammary pad on theleft side. The generation of the ER HT17 and ER⁺ HT33 patient-derivedxenografts has been described previously (31). Animal handling andassociated procedures were approved by the Institutional Animal Care andUse Committee (IACUC). Additional information is detailed inSupplementary Methods.

Intravital Imaging. Intravital imaging was performed using acustom-built two-laser multiphoton microscope, as previously described(57). Mice were anesthetized using 0.75-2.5% isofluorane, depilated. Askin flap procedure, previously developed (58), was performed byexposing the 4^(th) or 5^(th) mammary fat pad. Given the early stage ofcarcinoma and small tumor size, this necessitated the development of acustom fixturing technique where the exposed tissue was stabilized byaffixing the edge of a 10-mm window fitted with an 8-mm clear aperturerespectively with cyanoacrylate. The mouse was then placed on afixturing plate, fitted to the respective window, on the microscope xystage and imaging was performed in the center of the window away fromthe glue. The animal was placed in a heated chamber, AirTherm ATX forcedair heater (WPI Inc.), maintained at physiologic temperature during thecourse of imaging, and supplemented with 50-100 uL of PBS per hour viathe tail vein catheter. As previously described (1), three milligrams of155-kDa TMR-dextran (Sigma) were administered via the catheter tovisualize the vasculature. All images were reconstructed and analyzed inImageJ (59), as described in Supplementary Methods.

Histology and TMEM Immunohistochemistry. Breast tumors and lungs wereisolated, rinsed in PBS, fixed in 10% neutral buffered formalin for 48hours, dehydrated and embedded in paraffin. Sections (5 μm) were stainedwith H&E or TMEM triple-stain immunohistochemistry, as previouslydescribed (3).

Immunofluorescence. Slides were deparaffinized by melting at 60° C. inan oven equipped with a fan for 20 minutes, followed by 2×xylenetreatment for 20 minutes. Slides were rehydrated and antigen retrievalwas done in 1 mM EDTA (pH 8.0) or 1× citrate buffer (pH 6.0) (DiagnosticBioSystems) at 97° C. for 20 minutes in a conventional steamer.Endogenous peroxidase was blocked by using 0.3% hydrogen peroxide inwater, followed by incubation of slides in a blocking buffer solution(10% FBS, 1% BSA, 0.0025% fish skin gelatin in 0.05% PBST) for 60minutes at room temperature. The following primary antibodies were usedin different combinations, depending on the experiment: chickenanti-Mena^(INV) (0.25 ug/mL, generated in-house in the lab of John S.Condeelis), rabbit anti-Cd31 (1:400; 77699s; Cell Signaling), rabbitanti-Vegf (1:2,000; Rb 9031-PO-A; Thermo), rat anti-Tie2 (1:100;16-5987-82; eBioscience), rabbit anti-Iba1 (1:6,000; 019-19741; Wako),rat anti-endomucin (1:500; sc-65495; Santa Cruz), rabbit anti-TMR(1:1,000; A-6397; Life Technologies). Secondary antibody treatment wasperformed using HRP-conjugated antibodies, and was followed by tyramidesignal amplification (TSA), using the Perkin Elmer; Opalm 4-colorFluorescent IHC kit, according to the manufacturer's directions. Allslides were imaged on the Pannoramic 250 Flash II digital whole slidescanner, using a 20×0.75NA objective lens. Image analysis was performedin ImageJ, detailed in Supplementary Methods.

Gene Expression Analysis. Total RNA was extracted from formalin-fixedparaffin-embedded (FFPE) tissues using deparaffinization solution(Qiagen) and RNeasy FFPE Kit (Qiagen), followed by DNase treatment. AnRT-PCR method SYBR Green (Qiagen) was used to measure expression levelsof total Mena (PanMena), as well as of the specific Mena isoforms,Mena11a and Mena^(INV), as described (29), with slight modifications, asdetailed in Supplementary Methods. Mena^(Calc) expression has beenpreviously defined as the expression level of all Mena isoforms combinedafter subtraction of Mena 11a from PanMena (2).

Circulating Tumor Cells. Mice were anesthetized with 3.5-4.5%isoflurane, and blood was taken from the right ventricle by heartpuncture, using 25G needles coated with heparin. Erythrocytes werelysed, using 10 ml of 1×RBC lysis buffer (multi-species, eBioscience).Cancer cells were quantified, as previously described (31, 60).

Statistical analysis. All statistical tests are justified for everyfigure. Sample size was calculated based on significance level (adjustedfor sidedness) of 0.025, probability of type II error of 0.2(statistical power of 0.8) and expected difference in means equal to 1.2standard deviation (SD) units, based on the assumption that the SD ofthe response variable was 1 unit. Data are presented as dot plots withtheir means and SDs. Significant differences between groups weredetermined using nonparametric statistical tests, i.e. the Mann-WhitneyU-test for unpaired and Wilcoxon test for paired samples. Correlationswere performed using Pearson's correlation and coefficient ofdetermination (R²), and data are presented as scatterplots withfit-lines and p-values. To investigate for differences of a binaryoutcome (i.e. incidence of metastasis) between two groups,cross-tabulation and chi-square tests were performed. All p-values of<0.1 are reported in graphs, but significance level for statisticaltesting was set to p<0.05.

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1. A method of treating a subject for a tumor, wherein the subject hasreceived or is receiving chemotherapy treatment for the tumor,comprising a) identifying the subject as having an increased risk ofmetastasis in response to chemotherapy by performing or having performeda quantification of Mena^(Calc), Mena^(INV) or a TMEM score of thetumor, and comparing to a predetermined control level of Mena^(Calc),Mena^(INV) or TMEM score, wherein a subject having a Mena^(Calc),Mena^(INV) or a TMEM score above the respective predetermined controllevel identifies the subject as having an increased risk of metastasis,and b) when a subject is identified in step a) as having an increasedrisk of metastasis in response to chemotherapy, either (1) ceasingchemotherapy on the subject and administering a targeted therapy,immunotherapy or radiotherapy to treat the cancer, or (2) administeringa chemotherapy and an amount of (i) a Tie-2 inhibitor effective toreduce chemotherapy-induced metastasis or chemotherapy-induced cancercell dissemination, or (ii) a TMEM activity inhibitor, to the subjecteffective to treat a tumor.
 2. The method of claim 1, wherein when asubject is identified in step a) as having an increased risk ofmetastasis in response to chemotherapy, the chemotherapy and an amountof (i) a Tie-2 inhibitor effective to reduce chemotherapy-inducedmetastasis or chemotherapy-induced cancer cell dissemination, or (ii) aTMEM activity inhibitor, is administered to the subject.
 3. The methodof claim 1, wherein the TMEM activity inhibitor comprises a CSF1Rinhibitor, a VEGFR inhibitor, or a MENA inhibitor.
 4. The method ofclaim 1, further comprising obtaining a predetermined control level forMena^(Calc), Mena^(INV) or TMEM score for the subject by obtaining aMena^(Calc), Mena^(INV) or TMEM score from a tumor sample from thesubject prior to any chemotherapy being initiated on the subject. 5.(canceled)
 6. The method of claim 1, wherein the Tie-2 inhibitor isrebastinib(4-[4-[(5-tert-butyl-2-quinolin-6-ylpyrazol-3-yl)carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide).7. The method of claim 1, wherein the chemotherapy is an anti-tubulinchemotherapy.
 8. The method of claim 1, wherein the chemotherapy is ataxane.
 9. The method of claim 1, wherein the chemotherapy is paclitaxelor eribulin.
 10. The method of claim 1, wherein the tumor is a breastcancer tumor.
 11. The method of claim 10, wherein the breast cancer isan adenocarcinoma.
 12. The method of claim 10, wherein the breast canceris Human Epidermal Growth Factor 2 Negative.
 13. (canceled)
 14. Themethod of claim 10, wherein the breast cancer is a Stage IV breastcancer.
 15. The method of claim 1, wherein the chemotherapy is aneoadjuvant therapy.
 16. The method of claim 1, wherein the metastasisis a lung metastasis, bone metastasis, lymph node metastasis, livermetastasis or brain metastasis.
 17. A method of reducingchemotherapy-induced tumor microenvironment of metastasis (TMEM)activity in a patient comprising administering, to a patient with acancer subject to a chemotherapy treatment, an amount of a Tie-2inhibitor effective to reduce chemotherapy-induced TMEM activity. 18.The method of claim 17, wherein the Tie-2 inhibitor is rebastinib(4-[4-[(5-tert-butyl-2-quinolin-6-ylpyrazol-3-yl)carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide).19. The method of claim 17, wherein the chemotherapy is an anti-tubulinchemotherapy.
 20. The method of claim 17, wherein the chemotherapycomprises administering a taxane.
 21. The method of claim 17, whereinthe chemotherapy comprises administering paclitaxel or eribulin.
 22. Themethod of claim 17, wherein the cancer is a breast cancer.
 23. Themethod of claim 22, wherein the breast cancer is an adenocarcinoma. 24.The method of claim 22, wherein the breast cancer is Human EpidermalGrowth Factor 2 Negative.
 25. (canceled)
 26. The method of claim 22,wherein the breast cancer is a Stage IV breast cancer.
 27. The method ofclaim 15, wherein the chemotherapy is a neoadjuvant therapy.
 28. Themethod of claim 15, wherein the neoadjuvant therapy comprisesdoxorubicin and cyclophosphamide.
 29. A method of inhibiting metastasisof a cancer comprising administering, to a patient with a cancer, anamount of a Tie-2 inhibitor effective to inhibit metastasis of a cancer.30. The method of claim 1, wherein the patient or subject has beenidentified as likely having a poor long-term response to chemotherapy bycomprising determining, in a sample obtained from the subject, the levelof Mena^(Calc), Mena^(INV) or a TMEM score thereof, and comparing to apredetermined control level of Mena^(Calc), Mena^(INV) or TMEM score,respectively, and identifying the subject as having a poor long-termresponse to chemotherapy wherein a subject is identified as likelyhaving a poor long-term response to chemotherapy when the sampleobtained from the subject has a level of Mena^(Calc), Mena^(INV) or TMEMscore above the predetermined control level of Mena^(Calc), Mena^(INV)or TMEM score, respectively.
 31. (canceled)
 32. The method of claim 1,wherein the patient or subject has been identified as likely having atumor resistant to a receptor tyrosine kinase (RTK) inhibitor therapy bycomprising determining, in a sample of the tumor obtained from thesubject, the level of Mena^(Calc), Mena^(INV) or a TMEM score thereof,and comparing to a predetermined control level of Mena^(Calc),Mena^(INV) or TMEM score, respectively, and identifying the subject ashaving a tumor resistant to RTK inhibitor therapy, wherein a subject isidentified as likely having a tumor resistant to RTK inhibitor therapywhen the sample obtained from the subject has a level of Mena^(Calc),Mena^(INV) or TMEM score above the predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively. 33-34. (canceled)35. A method of reducing chemotherapy-induced metastasis, orchemotherapy-induced cancer cell dissemination, comprisingadministering, to a patient with a cancer subject to a chemotherapytreatment, an amount of (i) an inhibitor of Mena function or (ii) aninhibitor of Mena expression effective to reduce chemotherapy-inducedmetastasis or chemotherapy-induced cancer cell dissemination.
 36. Themethod of claim 35, wherein the inhibitor of Mena is an interfering-RNA,an interfering-microRNA, a Mena gene edit, or a Mena gene splicingsuppressor.
 37. The method of claim 35, wherein the inhibitor of Mena isan inhibitor of Mena function and is a small molecule inhibitor of, oran aptamer which inhibits, Mena's interaction with a target protein. 38.The method of claim 35, wherein the inhibitor of Mena is an inhibitor ofMena's interaction with a target protein which is PTP1b, SHIP2, Rac1 ora receptor tyrosine kinase.
 39. The method of claim 35, wherein thechemotherapy is a neoadjuvant therapy.
 40. The method of claim 35,wherein the chemotherapy is an anti-tubulin chemotherapy.
 41. The methodof claim 39, wherein the chemotherapy comprises administering a taxane.42. The method of claim 39, wherein the chemotherapy comprisesadministering paclitaxel or eribulin.
 43. The method of claim 35,wherein the chemotherapy is a topoisomerase inhibitor, an intercalatingagent, a DNA cross-linking agent, or an alkylating agent.
 44. The methodof claim 35, wherein the cancer is a breast cancer.
 45. The method ofclaim 44, wherein the breast cancer is an adenocarcinoma.
 46. The methodof claim 44, wherein the breast cancer is Human Epidermal Growth Factor2 Negative.
 47. (canceled)
 48. The method of claim 44, wherein thebreast cancer is a Stage IV breast cancer.
 49. The method of claim 35,wherein the metastasis is a lung metastasis, bone metastasis, lymph nodemetastasis, liver metastasis or brain metastasis.
 50. A method ofreducing chemotherapy-induced tumor microenvironment of metastasis(TMEM) activity in a patient comprising administering, to a patient witha cancer subject to a chemotherapy treatment, an amount of (i) aninhibitor of Mena function or (ii) an inhibitor of Mena expressioneffective to reduce chemotherapy-induced TMEM activity.
 51. A method ofinhibiting metastasis of a cancer comprising administering, to a patientwith a cancer, an amount of (i) an inhibitor of Mena function or (ii) aninhibitor of Mena expression effective to inhibit metastasis of acancer.
 52. The method of claim 35, wherein the patient or subject hasbeen identified as likely having a poor long-term response tochemotherapy by comprising determining, in a sample obtained from thesubject, the level of Mena^(Calc), Mena^(INV) or a TMEM score thereof,and comparing to a predetermined control level of Mena^(Calc),Mena^(INV) or TMEM score, respectively, and identifying the subject ashaving a poor long-term response to chemotherapy wherein a subject isidentified as likely having a poor long-term response to chemotherapywhen the sample obtained from the subject has a level of Mena^(Calc),Mena^(INV) or TMEM score above the predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively.
 53. The method ofclaim 35, wherein the patient or subject has been identified as likelyhaving a tumor resistant to a receptor tyrosine kinase (RTK) inhibitortherapy by comprising determining, in a sample of the tumor obtainedfrom the subject, the level of Mena^(Calc), Mena^(INV) or a TMEM scorethereof, and comparing to a predetermined control level of Mena^(Calc),Mena^(INV) or TMEM score, respectively, and identifying the subject ashaving a tumor resistant to RTK inhibitor therapy, wherein a subject isidentified as likely having a tumor resistant to RTK inhibitor therapywhen the sample obtained from the subject has a level of Mena^(Calc),Mena^(INV) or TMEM score above the predetermined control level ofMena^(Calc), Mena^(INV) or TMEM score, respectively.
 54. The method ofclaim 1, wherein the patient or subject is a human patient or subject.